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usb: cdns3: gadget: fix resource leak on gadget init failure

PATCH 吴永超 1 participant 1 message Mar 30 USB

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Quoted 3 lines · Peter Chen

I have two questions:
- What exactly resource is leaked?
- Do you call cdns_drd_host_on before setup host?

For the first question:
The DRD hardware is left in gadget mode while software state remains INACTIVE, creating hardware/software state inconsistency. I will update the commit title to "usb: cdns3: gadget: fix state inconsistency on gadget init failure" to better reflect this.

For the second question:
When gadget start fails, the role state is not set to CDNS_ROLE_STATE_ACTIVE. When switching to host via:
echo host > /sys/class/usb_role/13180000.usb-role-switch/role

The flow is:
cdns_role_set()

    -> cdns_role_stop()
         if (cdns->roles[role]->state == CDNS_ROLE_STATE_INACTIVE)
             return;  // Skips cleanup because state is still INACTIVE

This violates the DRD controller design specification (Figure22), which requires returning to idle state before switching roles.

Error logs:

[  516.440698][ T4992] configfs-gadget 13180000.usb: failed to start g1: -19
[  516.442035][ T4992] cdns-usb3 13180000.usb: Failed to add gadget
[  516.443278][ T4992] cdns-usb3 13180000.usb: set role 2 has failed
...
echo host > /sys/class/usb_role/13180000.usb-role-switch/role
[ 1301.375722][ T5000] xhci-hcd xhci-hcd.1.auto: xHCI Host Controller
[ 1301.377716][ T5000] Internal error: synchronous external abort: 96000010 [#1] PREEMPT SMP

...

I will prepare v2 with Fixed-by tag and Cc to stable tree.

-----邮件原件-----
发件人: Peter Chen (CIX) <[email protected]>
发送时间: 2026年3月30日 13:52
收件人: Yongchao Wu <[email protected]>
抄送: Pawel Laszczak <[email protected]>; Roger Quadros <[email protected]>; Greg Kroah-Hartman <[email protected]>; [email protected]; [email protected] 主题: Re: [PATCH] usb: cdns3: gadget: fix resource leak on gadget init failure

Quoted 15 lines · Yongchao Wu

When cdns3_gadget_start() fails, the DRD gadget is left in an initialized state, causing a resource leak. When switching to host mode, the stale state triggers a synchronous external abort in xhci_gen_setup(), leading to kernel panic:

[  1301.377716][ T5000][E] Internal error: synchronous external abort: 
96000010 [#1] PREEMPT SMP [  1301.382485][ T5000][I] pc : 
xhci_gen_setup+0xa4/0x408 [  1301.393391][ T5000][I] backtrace:
    ...
    xhci_gen_setup+0xa4/0x408    <-- CRASH
    xhci_plat_setup+0x44/0x58
    usb_add_hcd+0x284/0x678
    ...
    cdns_role_set+0x9c/0xbc        <-- Role switch
Quoted 4 lines

Fix by calling cdns_drd_gadget_off() in the error path to properly clean up the DRD gadget state. This prevents both the resource leak and the kernel panic during role switching.

Good catch.

I have two questions:
- What exactly resource is leaked?
- Do you call cdns_drd_host_on before setup host?

Besides, you may add Fixed-by tag and Cc to stable tree.

Peter

Quoted 22 lines
Signed-off-by Yongchao Wu <[email protected]>
---
 drivers/usb/cdns3/cdns3-gadget.c | 1 +
 1 file changed, 1 insertion(+)
drivers/usb/cdns3/cdns3-gadget.c +1 -1
index d59a60a16..4cc3f2ffb 100644
@@ -3428,6 +3428,7 @@ static int __cdns3_gadget_init(struct cdns *cdns)
 	ret = cdns3_gadget_start(cdns);
 	if (ret) {
 		pm_runtime_put_sync(cdns->dev);
+		cdns_drd_gadget_off(cdns);
 		return ret;
 	}
 
--

2.43.0

Signature · 2 lines
Best regards,
Peter